This invention relates generally to electrical terminals and more specifically to electrical ground terminals for use with wedgebase lamp bulbs.
Wedgebase lamp bulbs may be of the single or dual filament type. The single filament type has two contact wires for energizing the filament which emerge from the end of the wedgebase and extend over onto opposite flat sides of the wedgebase so that there is one contact wire adjacent each lateral side of the wedgebase.
On the other hand the dual filament type has two sets of contact wires for energizing the respective two filaments. These four contact wires emerge from the end of the wedgebase and extend over onto opposite flat sides of the wedgebase so that there is one contact wire on each flat side adjacent each lateral side of the wedgebase. This results in a contact area for the dual filament lamp bulb which is thicker than the contact area for the single filament lamp bulb by the thickness of one contact wire.
These two types of lamp bulbs are interchangeable in lamp bulb sockets in the sense that the dual filament lamp bulb can be used in a lamp socket designed for a single filament lamp bulb. In this case, the dual filament lamp bulb acts as a single filament lamp bulb. This interchangeability requires a common ground terminal which can be used with either the single filament lamp bulb with its two contact wires or the dual filament lamp bulb with its four contact wires.
In the past, these common ground terminals have had the drawback that the spring contact arms of the common ground terminal are deflected ore by the wedgebase of the dual filament lamp bulb because of the added thickness which is due to the presence of a second contact wire on the opposite side of the wedgebase in the vicinity of each lateral side. Consequently these known common ground terminals produce a contact force which varies considerably depending upon the type of wedgebase lamp bulb that is being used. Moreover these known common ground terminals cannot be designed for the optimum contact force with either type lamp bulb because optimizing the design for one type introduces the possibility of either exceeding the elastic limit of the terminal material or producing an inadequate contact force when the other type lamp bulb is used.